1. Field of the Invention
This document relates to an ink composition and a method of forming a pattern using the same.
2. Related Art
In general, a process for forming a fine pattern applied in information storage, small-sized sensors, optical crystal and optical elements, microelectromechanical devices, display devices, displays, and semiconductors is a photolithographic method for forming a fine pattern by using light.
In the related art photolithographic method, a circuit line-width or a pattern line-width is dependent on a wavelength of the light used in the exposure process. Considering the current technological level, it is very difficult to form a fine pattern of 70 nm or smaller on a substrate by using a photolithographic method due to the interference of light. Further, as patterns become hyperfine, high-priced equipments, such as exposure equipments, are require, and this leads to an increase in initial investment cost and a sharp rise in the price of a high-resolution mask, thereby decreasing efficiency. The problem of having to use high-priced equipments ultimately serves as another factor of cost increase.
Besides, a considerable processing time is needed because exposure, post-exposure baking, development, post-development baking, etching, cleaning, etc. should be carried out whenever a pattern is formed. Also, a photoprocess needs to be repeated a plurality of times, thus to deteriorate productivity.
As a method to solve these problems, an imprint lithographic method and a roll-printing technique were proposed. The imprint lithographic method, which was invented by Stephen Chou et. al., Princeton University, USA, is a method for forming a fine pattern by manufacturing a necessary shape on the surface of an organic material or polymer having a relatively high strength and then imprinting the material into another material for patterning.
More specifically, the imprint lithographic method is a technique for forming a pattern by preparing an inorganic or polymer mold on which a desired pattern is formed, facing the mold with a curable composition coated on a metal film or an organic film and thermosetting or photocuring the mold and the curable composition. Such an imprint lithographic method has an advantage over the related art photolithographic method in terms of process simplification and fine pattern formation. Regarding the roll-printing technique, Korean Patent Application No. 2006-0005482 (Laid-Open Patent Publication No. 10-2007-76292) specifically discloses a roll-printing apparatus and a method of manufacturing a display device by using the same. It is mentioned that the roll-printing method is applicable to FEDs (field emission displays), organic EL (electroluminescent) devices, and PDPs (plasma display panels) and the manufacturing process is simplified, and it is disclosed that the accuracy of a pattern is guaranteed even after repeated printing.
In the roll-printing technique, a pattern is directly transferred to a substrate on which a fine pattern is to be formed by using a blanket and a cliché instead of a high-resolution mask used to form a pattern in the related art photolithography. Such a roll-printing technique has improved the deformability with a mold by an alignment using a blanket serving as a stamp, and has enhanced productivity and working efficiency by employing a thermosetting process. Further, this technique is suggested as an alternative way to substantially reduce a complex process that is performed through various steps, such as exposure of photolithography, development and so on, and incidental process expenses resulting from the complexness of the process.
However, if an ink composition with high flowability and evaporation rate is used upon formation of a fine pattern by using the related art imprint technique and roll-printing technique, the ink composition soaks into the blanket, which is a blanket, thereby causing contamination of the blanket. This leads to an increase in process standby time and a reduction of the number of times of use in the use of the blanket.
Moreover, when a cleaning operation is carried out by physical contact in order to remove impurities on the ink composition generated by the contamination of the blanket, the surface is easily damaged by friction. Also, when an imprint or roll-printing process is carried out in a state that the ink composition of the blanket is not removed, a fine pattern of the ink composition is wrongly formed on a side of the substrate to be formed, or excessive quality defects occur. Therefore, there is a limit to continuous transfer of a fine pattern, and there is a difficulty in increasing the accuracy of a fine pattern.